microwave magnetron

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Anyone know what the actual difference between a 2M240H(PA) and a 2M240H might be?
I have a duff 2M240H(PA) from a Siemens branded microwave. £140 for the genuine part from the authorised spares vendor, £60 for generic on ebay
clearly the cheaper one is more attractive.
 
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No idea, but a new microwave is the same price as those parts.
If my microwave broke I wouldn't be even considering any repair.
I tend to agree with you but that's NOT WHAT WE ARE ABOUT IS IT. Get with the program: repair don't replace. there is a war on you know. Also this is a sexy unit from a fitted kitchen, so a £30 Tesco's unit is not really a replacement in this case. (not my kitchen, a friend's with a much higher-maintenance wife than my own)
Anyway, I went to the tip and ripped through scrappers until I got booted out. Out of the 3 mags that I recovered, one was very similar. so I fitted it and now the microwave seems to work fine. (tested it boiling a bowl of water).

seems to be a dearth of information on the www about uwave oven mags, which makes me slightly suspicious that Im asking google the wrong questions.
basically, "what do the part numbers mean?".
all the scrapper mags I've got seem to begin with 2M. I imagine that this might pertain to the basic product ie 2Ghz Magnetron, but there are usually at least 2 other numbers/letters and a suffix.

power - does this just go with size?
antenna height-above-gasket. thats got to be important re tuning the cavity? the one I used is about 5mm different from the original part but I dont see any significant change in performance nor smoke, arcing, etc.

A big attraction of the fitted units seems to be that the space is generally bigger than in a cheap oven. also there is no turntable in the big fitted unit. that seems potentially dangerous. I wonder if there is a way of electronically driving the mag that means they can fill-in the nulls that must be set up within the cooking space?
I noticed when carefully reading the labels on the mag "do not use without a microwave absorbing load". that warning is not translated through to the oven user. (is it?)
Ever since understanding RF basics Ive always thought it odd that general public have a fear of putting metal into a microwave but nobody worries about running a microwave empty.

personally I take great delight in microwaving metal parts.

there is a significant demographic of people that wait a few seconds for the microwaves to "die down" before opening the door.

so many questions.
so little care.

Basically, this poster is of the opinion that, as long as the magnetron is broadly physically similar, and will orient correctly for the fan to cool it in situ, any 2M magnetron can be replaced with any other 2M magnetron. I will go further: Most cheap microwaves fail on corrosion or the turntable, so the chances are good that any given scrap microwave will have a serviceable magnetron. Ergo, a sexy fitted microwave (which are the only ones worth considering a repair on) can have its otherwise expensive mag replaced essentially for free.


"correct" part in this case would have cost £134.
 
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Go to a radio club, they use the magnetron to transmit and receive with, and do reuse the units out of micro waves, I attended a great lecture by the late Sir Richard Davies in Suffolk about the early days or radar and the move to using UHF and the finding of dead seagulls which it seems had landed ready cooked.

It was at the time thought we could harness the power and build a death ray to aim at enemy planes, it was shown we could not do this, but the research showed we could cook food, it also showed the dangers of microwave energy, I know on mountain sites on the Falklands only woman could work at height as the micro waves made men sterile.

We heard all sorts of horror stories about people looking down wave guides etc. Enough so I decided 70 cm was as high as I wanted to play with, in the main sticking to 2 meter sets.

It is a case of fools rush in where angles fear to tread.
 
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Yes, up to a point, but it is a matter of degree.
Some fools do manage to get a degree, there is no fool like an old fool, and I have a degree! Not a very good one, but still a degree.

I will admit we did a lot of walking around shops to find a microwave with stainless steel insides, so it does not start to rust away as soon as the little wheels on the turn table wear through the paint. It would say stainless steel, but would find only outside stainless steel, what is the point of that, outside does not wear or rust.

Today there is a new kid on the block, the air frier, so the microwave and main oven are used less, I have looked at some of the Siemans built in microwaves at £800 clearly a special which is rated 16 amp so needs hard wiring, it has a stainless steel cavity, but one has to question the data sheet, 1000 watt microwave needing a 16 amp supply?

There are specials, and yes I remember a microwave blowing fuses as lab technicians were used it to dry samples so effectively running it empty. If you have a wave meter and can test it for leakage, then OK I suppose safe enough, I have only worked in one place where we had the tester for microwaves, I remember a load being condemned, and also them all then passing after we got the guy to retest with his mobile phone switched off.
 
Ever since understanding RF basics Ive always thought it odd that general public have a fear of putting metal into a microwave but nobody worries about running a microwave empty.

The instruction say 'no metal', but it is fine to include the likes of a single spoon, in an insulated dish, in the food. Two spoons in close contact is a definite no,no. Putting food in a metal container also will not work, because the food is shielded by the metal. Nor should you put anything in with metallic paint on it, the paint will ignite.
 
The instruction say 'no metal', but it is fine to include the likes of a single spoon, in an insulated dish, in the food. Two spoons in close contact is a definite no,no. Putting food in a metal container also will not work, because the food is shielded by the metal. Nor should you put anything in with metallic paint on it, the paint will ignite.
why not two spoons in close contact?
arcing could feasibly lead to nasty smoke, fumes or even metal fire (or arcing to the cavity) which indirectly could cause significant damage. but just arcing within the cavity - that's fine (??) - it represents energy being consumed (turned to heat) within the cavity, which (presumably) is preferable to no energy being consumed within the cavity. ??
I seem to be thinking of it like running a Tx into a very mismatched load
I feel that the cavities must be sculpted "just so", so that there is a standing wave pattern in just the right places that minimal energy is reflected back towards the mag
or are they like valves and sort of oblivious to high SWR
 
why not two spoons in close contact?

Because the two would have a high RF voltage between them, so at the point of contact, they would be destroyed by the arc.

'or are they like valves and sort of oblivious to high SWR'

They are a thermionic valve..
 

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